I don't know about AI, but there are already computer programs that try many different combinations of, for example, chemical structures with known pharmacological properties and then output new drugs that could possibly be used to treat something. Of course you have to verify with research and studies.

I'm sure there will be AI's or machine learning programs, if not already, that can do this as well and perhaps improve upon the process. But they would need to be specifically trained for that purpose. ChatGPT is a LLM, it's made to generate language that fits a given prompt, I would not expect it to be great at creating cancer treatments and I'm not sure why we needed a study to learn that. OpenAI tells you already that the results can be inaccurate or outright wrong.